Sean Penn: Action Hero? Stranger things have happened -- must we remind you that Liam Neeson is Hollywood's No. 1 butt-kicker? Even so, it's a tad strange to think of the stoic Penn taking part in car chases and gunfights, but that seems like it's close to happening.

According to The Hollywood Reporter, the two-time Oscar winner is close to signing on to 'The Prone Gunman', which is based on the book of the same name by author Jean-Patrick Manchette and will see the intense thespian playing an assassin on the run.

'The Prone Gunman' focuses on Martin Terrier, a hired killer who wants out of the game so he can settle down and marry his childhood sweetheart. Naturally, the organization he works for won't let him go without a fight, so Terrier finds himself in a cat-and-mouse game with his former employers.

Legendary producer Joel Silver ('Lethal Weapon') will produce the film, which is currently looking for a director, while StudioCanal is fully financing. THR believes this could be the start of a new franchise, a la the Jason Bourne movie series.

Penn has never really dipped his toe into these waters before, although he came closest with 2005's 'The Interpreter', in which he played a Secret Service agent assigned to saving Nicole Kidman's life. However, we will see him in the upcoming 'Gangster Squad,' so perhaps he still has a few tricks up his sleeve. 'Prone Gunman' is said to have an existentialist and thoughtful tone (expect it to be more 'The American' than 'Taken'), so don't think Penn is remaking himself into Jason Statham just yet. However, at 52 years old, he'd be a most unlikely recipient of his own action franchise since, yes, one Liam Neeson.